Take the sim out, switch on. Enter *2767*2878# The phone will reset. If that doesn't work enter *2767*3855# this code will full reset the phone though.
If you have a serial lead you can read the code from the phone with various free softwares. Best place for these is schwantz-i.org the pass word for all of the files is i-ztnawhcs or ztnawhcs....It's one of them, but which escapes me just now.